Astrophysics. Why does not the moon rotate around its axis?
The moon does not rotate around the soy axis, is it? For many years scientists have been arguing on this topic, but there is no answer that would satisfy everyone. Everyone puts forward his own hypotheses and tries to prove them. To date, there is a controversial situation on this issue.
The shape of the moon
The study of the surface of the moon is of great interest in the scientific community. Some study it with the Earth, considering it as one whole system.
When the Moon makes its move around the Earth, then itsthe position relative to the Sun is also changing. To our planet is always the same side. The line that separates the halves is called the terminator. Since the Moon is a satellite, it moves in an orbit, the shape of which is ellipsoidal.
During its journey around the Sun, it seems thatThe illuminated side of the moon changes shape. However, the celestial body remains always round, and because of the change in the angle of incidence of the sun's rays on the surface, it seems that its shape has changed. Within a month the Moon is visible from the Earth in several different angles. The main ones are:
- new moon;
- first quarter;
- full moon;
- last quarter.
At the new moon, the moon is not visible in the sky, becauseThis phase corresponds to the location of the satellite between the Sun and the Earth. The light from the Sun to the Moon does not fall and, accordingly, does not fend off, so its half, seen from Earth, is not illuminated.
In the first quarter, the right half of the Moon is illuminated by the Sun, since it is at an angular distance of 90 ° from the luminary. In the last quarter the position is similar, only the left side is illuminated.
Coming to the fourth phase - the full moon, the Moon is located in opposition to the Sun, so it completely reflects the light falling on it, and from the Earth can be seen the entire lighted half.
Earth
In the 16th century it was proved that the Earth hasits own rotation. However, how it started and what preceded it is unknown. There are several theories about this. For example, when planets were formed, clouds of dust merged and founded a planet, at the same time they attracted other cosmic bodies. The clash of the planets with these bodies and could drive them, and then proceeded by inertia. This is one of the hypotheses that has not been clearly confirmed. In this connection, another question arises: Why does the moon not rotate around its axis? Let's try to answer.
Types of Moon rotation
A prerequisite is that the body canRotate around its own axis, is the presence of this axis, and the moon does not. The proof of this is presented in this form: The moon is a body that we will break into a large number of points. When rotating, these points describe trajectories in the form of concentric circles. That is, it turns out that they are involved in rotation. And in the presence of an axis, some points would remain stationary, and the side visible from Earth would change. This does not happen.
In other words, centrifugal forces directed toward the center are absent on the satellite, so the Moon does not spin either.
The motion of the celestial body
Proving their own rotation of the moon, scientists use different methods of research. One of them is the consideration of the motion of the Earth's satellite relative to the stars.
They are mistaken for immovable bodies, from whichthe countdown is in progress. Using this method, it turns out that relative to the stars, the satellite has its own rotation. In this version, when the question of why the moon does not rotate around its axis, the answer will sound that it is spinning. However, such an observation is incorrect. Since the centripetal control of the Moon is determined by the Earth, then it is necessary to study the possibilities of the celestial body with respect to the Earth.
Orbit or trajectory
To understand whether the Moon rotates around its axis, consider such concepts as "orbit" and "trajectory." They are different.
Orbit:
- closed and curve;
- shape - round or ellipsoidal;
- lies in one plane;
Trajectory:
- a curve having a beginning and an end;
- straight or curved shape;
- is in one plane or in three-dimensional.
Why does not the moon rotate around its axis? It is known that the body can participate only in two types of movement simultaneously. At the Moon these two admissible species are present: around the Earth and around the Sun. Accordingly, there can not be other kinds of rotation.
If we look at the trajectory of the Moon from Earth, we will see a complex curve.
The presence of the orbit is regulated by the law of conservation of momentum, but it can change if the angular momentum changes. Orbit - described by the laws of physics, trajectory - the laws of mathematics.
The Earth-Moon System
In some utilities, the Moon and the Earth are a singlewhole system. Mathematically, their common center of mass is calculated, which does not coincide with the center of the Earth, and it is asserted that rotation is going on around it. However, from the point of view of astrophysics, there is no rotation around this center, as can be seen by observing the Moon and the Earth through special modern equipment.
Why does not the moon revolve around its axis? Is it true? The rotation of the celestial body is spin-spin and spin-orbital. The moon performs a rotational spin-orbit motion around the axis passing through the center of the Earth.
People on Earth see all the time one side of the moon, and it does not change. For practical proof, you can experiment with a small weight.
Take the weights, tie it to a rope and twist. In this case, the weights will be the Moon, and the person holding the second end of the rope will be the Earth. Rotating around a weaver, a person sees only one side of it, that is, people on Earth see one side of the moon. Approached the second person, who has become at a distance, will see all sides of the weights while it does not rotate around its axis. The Moon has the same thing, it does not rotate around its axis.
Space age
For a long time, scientists have studied only the visiblethe side of the moon. There was no way to know what the opposite looks like. But with the development of the space age in the middle of the 20th century, mankind could see the second side.
As it turned out, the lunar hemisphere is strikinglydiffer from each other. Thus, the surface of the side facing the Earth is covered with basalt spoons, and the surface of the second hemisphere is strewn with craters. These differences are still of interest to scientists. It is believed that many years ago the Earth had two satellites, one of which collided with the Moon and left such imprints on its surface.
Conclusion
The moon is a satellite whose behavior is not exactlystudied. Why does not the moon rotate around its axis? This question is asked by many scientists for several years and is unequivocally correct answer is not found. Some scientists believe that rotation still exists, but it is invisible to people, because the periods of the rotation of the moon around its axis and around the earth coincide. Other scientists deny this fact and recognize the circulation of the Moon only around the Sun and Earth.
The question of why the Moon does not rotate around its axis was considered in this article, and with the help of an example (about the weight) is proved.
